Organic light emitting diode display and method for manufacturing the same

ABSTRACT

An organic light emitting diode (OLED) display includes: a substrate; an organic light emitting diode formed on the substrate; a first inorganic layer formed on the substrate and covering the organic light emitting diode; an intermediate layer formed on the first inorganic layer and covering an area relatively smaller than the first inorganic layer; and a second inorganic layer formed on the first inorganic layer and the intermediate layer, and contacting the first inorganic layer at an edge thereof while covering a relatively larger area than the intermediate layer. A third inorganic layer may be formed on the second inorganic layer so as to contact the second inorganic layer at an edge thereof. At least one of the first, second and third inorganic layers is formed by an atomic layer deposition (ALD) method.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, andclaims all benefits accruing under 35 U.S.C. §119 from an applicationearlier filed in the Korean Intellectual Property Office on the 14^(th)of October 2011 and there duly assigned Serial No. 10-2011-0105429.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic light emitting diode (OLED)display and a manufacturing method thereof. More particularly, thepresent invention relates to an OLED display using thin filmencapsulation, and a manufacturing method thereof.

2. Description of the Related Art

Unlike a liquid crystal display, the OLED display has a self-emittingcharacteristic and does not need a separate light source such that thethickness and weight thereof are decreased. In addition, since the OLEDdisplay involves high quality characteristics such as low powerconsumption, high luminance, and short response time, it is spotlightedas a next generation display device for portable electronic appliances.

The OLED display includes a plurality of organic light emitting diodes,each having a hole injection electrode, an organic emission layer, andan electron injection electrode. Light is generate by energy generatedwhen exciton generated by combining electrons and holes in an organicemission layer falls from an exited state to a ground state, and theOLED display displays the image using the same.

However, the organic emission layer sensitively reacts to the externalenvironment such as moisture and oxygen. Thus, when the organic emissionlayer is exposed to moisture and oxygen, quality of the OLED display maydeteriorate. Accordingly, in order to protect an organic light emittingdiode and prevent permeation of moisture or oxygen into the organicemission layer, an encapsulation substrate may be attached in anair-tight manner to a display substrate where the organic light emittingdiode is formed, or a thin film encapsulation may be formed on theorganic light emitting diode.

In particular, the entire thickness of the OLED display can besignificantly reduced by using the thin film encapsulation rather thanusing the encapsulation substrate. Furthermore, it is advantageous torealize a flexible display.

However, the OLED display using the thin film encapsulation caneffectively prevent permeation of moisture or oxygen along a directionperpendicular to the substrate, but moisture or oxygen may be easilypermeated into the substrate along an interface of the thin filmencapsulation in a direction parallel to the substrate at an edge of thesubstrate.

The above information disclosed in this Background section is only forenhancement of an understanding of the background of the invention, andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention has been developed in an effort to provide anorganic light emitting diode (OLED) display that can be easilymanufactured by having a relatively small structure while effectivelysuppressing permeation of moisture and oxygen along a side surfacedirection.

An OLED display according to the present invention includes: asubstrate; an organic light emitting diode formed on the substrate; afirst inorganic layer formed on the substrate and covering the organiclight emitting diode; an intermediate layer formed on the firstinorganic layer and covering an area relatively smaller than the firstinorganic layer; and a second inorganic layer formed on the firstinorganic layer and the intermediate layer, and contacting the firstinorganic layer at an edge thereof while covering a relatively largerarea than the intermediate layer.

The first inorganic layer and the second inorganic layer may be layeredon the edge of the substrate.

The first inorganic layer may be formed through an atomic layerdeposition (ALD) method.

The intermediate layer may include at least one of a metal oxide layerand an organic layer.

The OLED display may further include an upper layer formed on the secondinorganic layer, and the upper layer may cover a relatively smaller areathan the second inorganic layer.

The upper layer may cover an area that is the same as the intermediatelayer.

The upper layer may include at least one of a metal oxide layer and anorganic layer.

The OLED display may include a third inorganic layer formed on thesecond inorganic layer and the upper layer and contacting the secondinorganic layer at an edge thereof while covering a relatively largerarea than the upper layer.

The first inorganic layer, the second inorganic layer, and the thirdinorganic layer may be layered on the edge of the substrate.

At least one of the second inorganic layer and the third inorganic layermay be formed through an ALD method.

A manufacturing method of an OLED display according to another exemplaryembodiment of the present invention includes: preparing a substrate;forming an organic light emitting diode on the substrate; forming afirst inorganic layer covering the organic light emitting diode; formingan intermediate layer on the first inorganic layer and covering an arearelatively smaller than the first inorganic layer; and forming a secondinorganic layer on the first inorganic layer and the intermediate layer,and contacting the first inorganic layer at an edge thereof whilecovering a relatively larger area than the intermediate layer.

The first inorganic layer and the second inorganic layer may be layeredon an edge of the substrate.

The first inorganic layer may be formed through an atomic layerdeposition (ALD) method.

The intermediate layer may include at least one of a metal oxide layerand an organic layer.

The manufacturing method of the OLED display may further include formingan upper layer on the second inorganic layer, wherein the upper layercovers an area relatively smaller than the second inorganic layer.

The upper layer may cover an area that is the same as the intermediatelayer.

The upper layer may include at least one of a metal oxide layer and anorganic layer.

The manufacturing method of the OLED display may further include forminga third inorganic layer on the second inorganic layer and the upperlayer, and contacting the second inorganic layer at an edge thereofwhile covering an area relatively larger than the upper layer.

The first inorganic layer, the second inorganic layer, and the thirdinorganic layer may be layered on the edge of the substrate.

At least one of the second inorganic layer and the third inorganic layermay be formed through the ALD method.

According to the exemplary embodiments of the present invention, theOLED display can have a relatively simple structure while effectivelysuppressing permeation of moisture and oxygen along the side surfacedirection.

In addition, damage to the organic light emitting diode during a processfor forming the thin film encapsulation can be minimized.

Furthermore, the OLED display can be effectively and easilymanufactured.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, in which likereference symbols indicate the same or similar components, wherein:

FIG. 1 is a cross-sectional view of an organic light emitting diode(OLED) display according to a first exemplary embodiment of the presentinvention;

FIG. 2 is an enlarged cross-sectional view of the OLED display of FIG.1;

FIG. 3 is a cross-sectional view of an OLED display according to asecond exemplary embodiment of the present invention;

FIG. 4 is a cross-sectional view of an OLED display according to a thirdexemplary embodiment of the present invention;

FIG. 5 is a cross-sectional view of an OLED display according to afourth exemplary embodiment of the present invention; and

FIG. 6 is a comparison table of an experiment example and a comparativeexample according to the first exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown.

As those skilled in the art will realize, the described embodiments maybe modified in various different ways, all without departing from thespirit or scope of the present invention.

In various exemplary embodiments, the same reference numerals are usedfor elements having the same configuration, and will be representativelydescribed in a first exemplary embodiment whereas, in other exemplaryembodiments, only elements different from those of the first exemplaryembodiment will be described.

The drawings are schematic and not proportionally scaled down. Relativescales and ratios in the drawings are enlarged or reduced for thepurpose of accuracy and convenience, and the scales are random and notlimited thereto. In addition, like reference numerals designate likestructures, elements, or parts throughout the specification. It will beunderstood that, when an element is referred to as being “on” anotherelement, it can be directly on another element or intervening elementsmay be present therebetween.

Exemplary embodiments of the present invention represent ideal exemplaryembodiments of the present invention in detail. As a result,modifications of diagrams are expected. Accordingly, exemplaryembodiments are not limited to specific shapes of shown regions, and forexample, also include modifications of the shape by manufacturing.

Hereinafter, an organic light emitting diode (OLED) display according toa first exemplary embodiment of the present invention will be describedwith reference to FIG. 1.

FIG. 1 is a cross-sectional view of an organic light emitting diode(OLED) display according to a first exemplary embodiment of the presentinvention.

As shown in FIG. 1, the OLED display 101 according to the firstexemplary embodiment of the present invention includes a substrate 110,an organic light emitting diode 70, and a thin film encapsulation 201.

The substrate 110 may be made of various materials known to a personskilled in the art, and the material may include glass, quartz, ceramic,and the like. In addition, the organic light emitting diode 70 is formedon the substrate 110. The organic light emitting diode 70 emits lightand the OLED display 101 displays an image.

The thin film encapsulation 201 protects the organic light emittingdiode 70 by covering the same. In addition, the thin film encapsulation201 has a multi-layered structure.

In the first exemplary embodiment of the present invention, the thinfilm encapsulation 201 includes a first inorganic layer 211,intermediate layers 221, 222, and 223, and a second inorganic layer 212.

The first inorganic layer 211 covers the organic light emitting diode70. The first inorganic layer 211 is disposed most adjacent to theorganic light emitting diode 70 among the layers of the thin filmencapsulation 201. That is, the first inorganic layer 211 becomes thelowest layer of the thin film encapsulation 201.

The intermediate layers 221, 222, and 223 are formed on the firstinorganic layer 211. The intermediate layers 221, 222, and 223 cover arelatively smaller area than the first inorganic layer 211. In furtherdetail, the intermediate layers 221, 222, and 223 expose edges of thefirst inorganic layer 211.

The second inorganic layer 212 is formed on the first inorganic layer211 and the intermediate layers 221, 222, and 223. The second inorganiclayer 212 covers a relatively larger area than the intermediate layers221, 222, and 223. In addition, the second inorganic layer 212 contactsthe first inorganic layer 211 at edges thereof.

That is, the thin film encapsulation 201 has a structure in which thefirst inorganic layer 211 and the second inorganic layer 212 aresequentially layered on the edges of the substrate 110, and thin filmencapsulation substrate 212 has a structure in which the first inorganiclayer 211, the intermediate layers 221, 222, and 223, and the secondinorganic layer 212 are sequentially layered on the organic lightemitting diode 70.

The first inorganic layer 211 and the second inorganic layer 212 may beformed of a material including at least one of Al₂O₃, TiO₂, ZrO, SiO₂,AION, AIN, SiON, Si₃N₄, ZnO, and Ta₂O₅.

In addition, the first inorganic layer 211 is formed through an atomiclayer deposition (ALD) method. According to the ALD method, the firstinorganic layer 211 may be formed by growing the above-stated inorganicmaterials at a temperature lower than 100° C. in order to prevent damageto the organic light emitting diode 70. The first inorganic layer 211formed through the ALD method has high density so that permeation ofmoisture or oxygen can be effectively suppressed.

The intermediate layers 221, 222, and 223 are formed of multi-layersincluding a metal oxide layer and an organic layer. FIG. 1 illustratesthat the intermediate layers 221, 222, and 223 have a triple-layeredstructure of a metal oxide layer, an organic layer, and a metal oxidelayer, but the first exemplary embodiment of the present invention isnot limited thereto. That is, the intermediate layers 221, 222, and 223may have various complex structures known to a person skilled in theart.

Meanwhile, the organic layer 222 is formed of a polymer-based material.The polymer-based material includes an acryl-based resin, an epoxy-basedresin, polyamide, and polyethylene.

In the first exemplary embodiment of the present invention, the firstinorganic layer 211 is formed most adjacent to the organic lightemitting diode 70. As described, the first inorganic layer 211, formedmost adjacent to the organic light emitting diode 70, is formed throughthe above-stated ALD method, and accordingly, damage to the organiclight emitting diode 70 during the process for forming the thin filmencapsulation 201 can be minimized.

In addition, the first inorganic layer 211 suppresses damage to theorganic light emitting diode 70 due to plasma or other impact during theprocess for forming the intermediate layers 221, 222, and 223.

The second inorganic layer 212 may also be formed using the ALD method,but it is not restrictive.

Furthermore, the substrate 110, the first inorganic layer 211, and thesecond inorganic layer 212 have relatively excellent bonding forcetherebetween, and thus when the first inorganic layer 211 and the secondinorganic layer 212 are sequentially layered on the edge of thesubstrate 110, permeation of moisture or oxygen along interlayerinterfaces in the side surface direction can be effectively suppressed.

In addition, the organic layer 222 of the intermediate layers 221, 222,and 223 have a relatively good planarization characteristic and can easeinterlayer stress. That is, the intermediate layers 221, 222, and 223may function to ease the interlayer stress between the first inorganiclayer 211 and the second inorganic layer 212.

Furthermore, the first inorganic layer 211 and the second inorganiclayer 212 may be manufactured using the same mask, and the intermediatelayers 221, 222, and 223 may be manufactured using the same mask. Thatis, the thin film encapsulation 201 can be formed using two types ofmasks. Therefore, compared to the general manufacturing of a thin filmencapsulation having a gradual structure, more than two masks are notrequired, and therefore the manufacturing process can be simplified andproductivity can be improved.

With such a configuration, the OLED display 101 according to the firstexemplary embodiment of the present invention can effectively suppresspermeation of moisture or oxygen along the interlayer interface in theside surface direction. Furthermore, the first inorganic layer 211 inthe thin film encapsulation 201 is formed most adjacent to the organiclight emitting diode 70 so that damage to the organic light emittingdiode 70 can be minimized.

In addition, the OLED display 101 according to the first exemplaryembodiment of the present invention has a relatively simple structure,and therefore the number of masks required during the manufacturingprocess can be minimized.

Hereinafter, structures of the organic light emitting diode 70 and athin film transistor for driving the organic light emitting diode 70formed on the substrate 110 in the OLED display 101 will now bedescribed in further detail with reference to FIG. 2.

FIG. 2 is an enlarged cross-sectional view of the OLED display of FIG.1.

The thin film transistor 10 includes a semiconductor layer 130, a gateelectrode 155, a source electrode 176, and a drain electrode 177.

In the first exemplary embodiment of the present invention, thesemiconductor layer 130 is formed of a polysilicon layer. However, thefirst exemplary embodiment of the present invention is not limitedthereto. Thus, the semiconductor layer 130 may be formed of an amorphoussilicon layer, an oxide semiconductor, or the like.

The gate electrode 155 is disposed on one area of the semiconductorlayer 130, and a gate insulation layer 140 is disposed between the gateelectrode 155 and the semiconductor layer 130. The gate electrode 155may be formed various conductive materials known to a person skilled inthe art. The gate insulation layer 140 may be formed so as to include atleast one of tetra ethyl ortho silicate (TEOS), silicon nitride(SiN_(x)), and silicon oxide (SiO₂). For example, the gate insulationlayer 140 may be a double layer formed by sequentially layering asilicon nitride layer having a thickness of 40 nm and a tetra ethylortho silicate layer having a thickness of 80 nm. However, the gateinsulation layer 140 is not limited to the above-described structure inthe first exemplary embodiment of the present invention.

The source electrode 176 and the drain electrode 177 respectivelycontact the semiconductor layer 130. The source electrode 176 and thedrain electrode 177 may be formed of various conductive materials knownto a person skilled in the art. The source electrode 176 and the drainelectrode 177 are separated from each other, and are insulated from thegate electrode 155. An interlayer insulation layer 160 may be disposedbetween the source electrode 176 and the drain electrode 177. Theinterlayer insulation layer 160 may be formed of various insulationmaterials known to a person skilled in the art.

The organic light emitting diode 70 includes a pixel electrode 710connected to the drain electrode 177 of the thin film transistor 10, anorganic emission layer 720 formed on the pixel electrode 710, and acommon electrode 730 formed on the organic emission layer 720. Inaddition, the organic light emitting diode 70 may further include apixel defining layer 190 having an opening partially exposing the pixelelectrode 710 and defining an emission area. The organic emission layer720 may emit light in the opening of the pixel defining layer 190.

In addition, in the first exemplary embodiment of the present invention,the structures of the thin film transistor 10 and the organic lightemitting diode 70 are not limited to the structure shown in FIG. 2. Thethin film transistor 10 and the organic light emitting diode 70 can havevarious structures that can be easily modified by a person skilled inthe art.

The OLED display 101 may further include a barrier layer 120 disposedbetween the thin film transistor 10 and the substrate 110. In furtherdetail, the barrier layer 120 may be disposed between the semiconductorlayer 130 and the substrate 110. For example, the barrier layer 120 mayhave a double-layered structure comprising a single layer of siliconnitride (SiN_(x)) and a double-layer of silicon nitride (SiN_(x)) andsilicon oxide (SiO₂). The barrier layer 120 functions to preventpermeation of unnecessary components, such as an impure element ormoisture, and makes the surface flat. However, the barrier layer 120 isnot a required constituent, and it may be omitted according to the typeand process condition of the substrate 110.

Hereinafter, a manufacturing method of the OLED display 101 according tothe first exemplary embodiment of the present invention will bedescribed.

First, the substrate 110 formed of a material such as glass, quartz, andceramic is prepared. In addition, the organic light emitting diode 70 isformed on the substrate 110.

Next, the first inorganic layer 211 covering the organic light emittingdiode 70 is formed on the substrate 110. In this case, the edge of thefirst inorganic layer 211 contacts the substrate 110. In addition, thefirst inorganic layer 211 is formed using a material including at leastone of Al₂O₃, TiO₂, ZrO, SiO₂, AlON, AlN, SiON, Si₃N₄, ZnO, and Ta₂O₅through the ALD method. According to the ALD method, the first inorganiclayer 211 can be formed by growing inorganic materials at a temperaturelower than 100° C. to prevent damage to the organic light emitting diode70. Furthermore, the first inorganic layer 211 formed using the ALDmethod has a high density so that permeation of moisture or oxygen canbe effectively suppressed.

Next, the intermediate layers 221, 222, and 223 are formed on the firstinorganic layer 211. In the first exemplary embodiment of the presentinvention, the intermediate layers 221, 222, and 223 are formed as amultiple layer including at least one of a metal oxide layer and anorganic layer.

In addition, the intermediate layers 221, 222, and 223 cover arelatively smaller area than the first inorganic layer 211. That is, theintermediate layers 221, 222, and 223 expose an edge of the firstinorganic layer 211. Therefore, the intermediate layers 221, 222, and223 are formed using a mask that is different from the first inorganiclayer 211.

The organic layer 222 of the intermediate layers 221, 222, and 223 maybe formed using a low temperature deposition method. The low temperaturedeposition method may use plasma. In this case, the first inorganiclayer 211 suppresses damage to the organic light emitting diode 70during the process for forming the organic layer 222. That is, the firstinorganic layer 211 can be formed without causing damage to the organiclight emitting diode 70, and can suppress damage to the organic lightemitting diode 70 during the post process.

Next, the second inorganic layer 212 is formed on the intermediatelayers 221, 222, and 223. In this case, the second inorganic layer 212covers a relatively larger area than the intermediate layers 221, 222,and 223. In addition, the second inorganic layer 212 contacts the firstinorganic layer 211 at the edge thereof. The second inorganic layer 212covers an area that is equivalent to the first inorganic layer 211, andin this case, the second inorganic layer 212 may be formed using thesame mask used to form the first inorganic layer 211.

As described, the thin film encapsulation 201 has a structure in whichthe first inorganic layer 211 and the second inorganic layer 212 arelayered on the edge of the substrate 110, and has a structure in whichthe first inorganic layer 211, the intermediate layers 221, 222, and223, and the second inorganic layer 212 are layered on the organic lightemitting diode 70.

Furthermore, since the substrate 110, the first inorganic layer 211, andthe second inorganic layer 212 have a relatively strong bonding force,permeation of moisture or oxygen along an interlayer interface in theside surface direction on the edge of the substrate 110 can beeffectively suppressed.

Meanwhile, the organic layer 222 of the intermediate layers 221, 222,and 223 forms a buffer between the first inorganic layer 211 and thesecond inorganic layer 212 so as to ease interlayer stress between thefirst inorganic layer 211 and the second inorganic layer 212.

With such a manufacturing method, the OLED display 101 that caneffectively suppress permeation of moisture or oxygen along theinterlayer interface in the side surface direction can be easilymanufactured using the manufacturing method of the OLED displayaccording to the first exemplary embodiment of the present invention.

In further detail, according to the first exemplary embodiment of thepresent invention, the thin film encapsulation 201 can effectivelysuppress the permeation of moisture or oxygen along the interlayerinterface in the side surface direction while being formed using twomasks.

In addition, according to the first exemplary embodiment of the presentinvention, the first inorganic layer 211 is first formed most adjacentto the organic light emitting diode 70, and thus damage to the organiclight emitting diode 70 during the process for forming the thin filmencapsulation 201 can be minimized.

Hereinafter, an OLED display according to a second exemplary embodimentof the present invention will be described with reference to FIG. 3.

FIG. 3 is a cross-sectional view of an OLED display according to asecond exemplary embodiment of the present invention.

As shown in FIG. 3, an OLED display 102 according to the secondexemplary embodiment of the present invention includes an intermediatelayer 222 formed as a single layer. In this case, the intermediate layermay be an organic layer. Thus, the intermediate layer 222 is made of apolymer-based material. In this regard, the polymer-based materialincludes an acryl-based resin, an epoxy-based resin, polyimide, andpolyethylene. In addition, the intermediate layer 222 may be formedusing a low temperature deposition method.

With such a configuration, the OLED display 102 according to the secondexemplary embodiment of the present invention can suppress permeation ofmoisture or oxygen along an interlayer interface in a side surfacedirection. In addition, a first inorganic layer 211 within the thin filmencapsulation 202 is formed most adjacent to the organic light emittingdiode 70, and thus damage to the organic light emitting diode 70 duringa process for forming the thin film encapsulation 202 can be minimized.

Furthermore, the OLED display 102 according to the second exemplaryembodiment of the present invention has a relatively simple structure,and therefore the number of masks required during the manufacturingprocess can be minimized.

The manufacturing method of the OLED display 102 according to the secondexemplary embodiment of the present invention is the same as themanufacturing method of the first exemplary embodiment except that theintermediate layer 222 is formed as a single layer.

Hereinafter, an OLED display according to a third exemplary embodimentof the present invention will be described with reference to FIG. 4.

FIG. 4 is a cross-sectional view of an OLED display according to a thirdexemplary embodiment of the present invention.

As shown in FIG. 4, an OLED display 103 according to the third exemplaryembodiment of the present invention further includes an upper layer 232formed on a second inorganic layer 212. The upper layer 232 covers anarea relatively smaller than the second inorganic layer 212. In furtherdetail, the upper layer 232 can cover an area that is the same as anintermediate layer 231. In this case, the upper layer 232 may be formedusing the mask used to form the intermediate layer 231. In addition,like the intermediate layer 231, the upper layer 232 may include atleast one of a metal oxide layer and an organic layer.

With such a configuration, the OLED display 103 according to the thirdexemplary embodiment of the present invention can effectively suppresspermeation of moisture or oxygen along the interlayer interference inthe side surface direction. In addition, a first inorganic layer 211within the thin film encapsulation 203 is formed most adjacent to theorganic light emitting diode 70, and thus damage to the organic lightemitting diode 70 during a process for forming the thin filmencapsulation 203 can be minimized.

The manufacturing method of the OLED display 103 according to the thirdexemplary embodiment of the present invention is the same as themanufacturing method of the first exemplary embodiment except that aprocess for forming the upper layer 232 on the second inorganic layer212 is additionally performed.

Hereinafter, an OLED display according to a fourth exemplary embodimentof the present invention will be described with reference to FIG. 5

FIG. 5 is a cross-sectional view of an OLED display according to afourth exemplary embodiment of the present invention.

As shown in FIG. 5, a thin film encapsulation 204 of an OLED display 104according to the fourth exemplary embodiment of the present inventionfurther includes an upper layer 242 formed on a second inorganic layer212 and a third inorganic layer 213 formed on the upper layer 242.

The upper layer 242 covers an area relatively smaller than the secondinorganic layer 212. In further detail, the upper layer 242 can cover anarea that is the same as an intermediate layer 241. In this case, theupper layer 242 may be formed using a mask used to form the intermediatelayer 241. Furthermore, like the intermediate layer 241, the upper layer242 may include at least one of a metal oxide layer and an organiclayer.

The third inorganic layer 213 is formed so as to contact the secondinorganic layer 212 at an edge thereof while covering a relativelylarger area than the upper layer 242. In further detail, the thirdinorganic layer 213 can cover an area that is the same as the secondinorganic layer 212 and, in this case, the third inorganic layer 213 maybe formed using a mask used to form the first inorganic layer 211 andthe second inorganic layer 212.

As described, the thin film encapsulation 204 has a structure in whichthe first inorganic layer 211, the second inorganic layer 212, and thethird inorganic layer 213 are layered on an edge of the substrate 110,and has a structure in which the first inorganic layer 211, theintermediate layer 231, the second inorganic layer 212, the upperportion 242, and the third inorganic layer 213 are layered on an organiclight emitting diode 70.

In addition, since the substrate 110, the first inorganic layer 211, thesecond inorganic layer 212, and the third inorganic layer 213 have arelatively strong bonding force, permeation of moisture or oxygen alongan interlayer interface in the side surface direction on the edge of thesubstrate 110 can be effectively suppressed.

With such a manufacturing method, the OLED display 104 that caneffectively suppress permeation of moisture or oxygen along theinterlayer interface in the side surface direction can be easilymanufactured using the manufacturing method of the OLED displayaccording to the first exemplary embodiment of the present invention.Furthermore, the first inorganic layer 211 within the thin filmencapsulation 204 is formed most adjacent to the organic light emittingdiode 70, and thus damage to the organic light emitting diode 70 duringthe process for forming the thin film encapsulation 204 can beminimized.

The manufacturing method of the OLED display 104 according to the fourthexemplary embodiment of the present invention is the same as themanufacturing method of the first exemplary embodiment except that theupper layer 242 and the third inorganic layer 213 are formed on thesecond inorganic layer 212.

However, the fourth exemplary embodiment of the present invention is notlimited thereto, and the thin film encapsulation 204 may include alayered inorganic layer comprising four or more layers, an intermediatelayer comprising three or more layers, and an upper layer.

Hereinafter, experiment examples and different comparative examplesaccording to the first exemplary embodiment of the present inventionwill be described with reference to FIG. 6.

FIG. 6 is a comparison table of an experiment example and a comparativeexample according to the first exemplary embodiment of the presentinvention.

The life-span evaluation experiments were performed with theexperimental example and the comparative examples, and the experimentwas performed under 50 times of acceleration life-span condition.

Comparative Example 1 includes one inorganic layer covering an organiclight emitting diode, and the inorganic layer was formed using an ALDmethod.

Comparative Example 2 includes an organic layer covering an organiclight emitting diode, and an inorganic layer formed on the organic layerand covering an area relatively larger than the area covered by theorganic layer. That is, a thin film encapsulation had a gradualstructure and two or more masks were used. The organic layer was formedusing a low temperature deposition method and the inorganic layer wasformed using the ALD method.

Comparative Example 3 includes an inorganic layer sealing anencapsulation substrate made of a known glass material and covering theencapsulation substrate. The inorganic layer was formed using the ALDmethod.

The Experimental Example has a structure according to the firstexemplary embodiment of the present invention, and materials ofinorganic and organic layers were the same as those of the comparativeexamples.

As shown in FIG. 6, although the ALD method was used, the ComparativeExample 1 having the thin film encapsulation formed of the inorganiclayer has a problem in light emission, and lighting was impossible after408 hours. In this regard, the experiment was performed under the 50times of acceleration life-span condition, and therefore 72 hours of theexperiment is substantially estimated to 360 hours.

According to Comparative Example 2, using the thin film encapsulationformed by forming the organic layer first and then forming the inorganiclayer using the ALD method, lighting was impossible after 168 hours andthus suppression of moisture permeation was weaker than that of theComparative Example 1.

According to Comparative Example 3, the inorganic layer formed throughthe ALD method was added on the encapsulation substrate made of a glassmaterial, a problem occurred in light emission after 168 hours, andlighting was impossible after 552 hours. Comparative Example 3 showsrelatively strong suppression of moisture permeation compared to othercomparative examples.

Meanwhile, the Experimental Example maintained light emission in goodstate even after 552 hours. That is, the Experimental Example has arelatively complicated structure while having a simple structure similarto Comparative Example 2, and has several times stronger permeationsuppression force than that of Comparative Example 3 having the mostexcellent permeation suppression force among the comparative examples.

As shown in the above-described experiments, the thin film encapsulationof the OLED display according to the exemplary embodiments of thepresent invention can minimize damage to the organic light emittingdiode during a process for forming the thin film encapsulation byforming the first inorganic layer most adjacent to the organic lightemitting diode first, and can effectively suppress permeation ofmoisture or oxygen along an interlayer interface in the side surfacedirection by layering inorganic layers having relatively excellentbonding force therebetween.

Furthermore, the number of masks required during a process using thethin film encapsulation can be minimized, thereby improvingproductivity.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An organic light emitting diode (OLED) displaydevice, comprising: a substrate; an organic light emitting diode formedon the substrate; a first inorganic layer formed on the substrate andcovering the organic light emitting diode; an intermediate layer formedon the first inorganic layer and covering an area relatively smallerthan the first inorganic layer; and a second inorganic layer formed onthe first inorganic layer and the intermediate layer and contacting thefirst inorganic layer at an edge thereof while covering a relativelylarger area than the intermediate layer; wherein the intermediate layercomprises at least one of an organic layer and a combination of a metaloxide layer and an organic layer.
 2. The OLED display device of claim 1,the first inorganic layer and the second inorganic layer being layeredon an edge of the substrate.
 3. The OLED display device of claim 2, thefirst inorganic layer being formed by an atomic layer deposition (ALD)method.
 4. The OLED display device of claim 1, further comprising anupper layer formed on the second inorganic layer, wherein the upperlayer covers a relatively smaller area than the second inorganic layer.5. The OLED display device of claim 4, wherein the upper layer covers anarea that is the same as the intermediate layer.
 6. The OLED displaydevice of claim 4, wherein the upper layer comprises at least one of ametal oxide layer and an organic layer.
 7. The OLED display device ofclaim 4, comprising a third inorganic layer formed on the secondinorganic layer and the upper layer, and contacting the second inorganiclayer at an edge thereof while covering a relatively larger area thanthe upper layer.
 8. The OLED display device of claim 7, wherein thefirst inorganic layer, the second inorganic layer, and the thirdinorganic layer are layered on an edge of the substrate.
 9. The OLEDdisplay device of claim 7, wherein at least one of the second inorganiclayer and the third inorganic layer is formed by an ALD method.